目的 篩選得到能夠有效防治玄參Scrophularia ningpoensis葉斑病的內(nèi)生真菌，并探討其作用機制。方法 以前期分離得到的玄參內(nèi)生真菌為候選菌株，玄參葉斑病病原菌草莖點霉（Phoma herbarum，PH）為指示菌，采用平板對峙法篩選內(nèi)生真菌拮抗菌株；采用活體葉片接種試驗，考察內(nèi)生真菌對玄參葉斑病的活體防治效果，測定玄參過氧化氫酶（catalase，CAT）防御酶、活性氧、水楊酸（salicylic acid，SA）等生理指標。采用ITS分子序列擴增對生防菌株進行菌種鑒定。結(jié)果 72株受試內(nèi)生真菌中，共有28株對草莖點霉菌存在顯著抑制作用，其中抑菌率最高的菌株為D90，抑菌率為（83.30±3.00）%。共有4株內(nèi)生真菌對玄參活體葉斑病具有顯著防治效果，分別為D1、D3、D18和D90，其病斑面積占比分別為（20.53±0.32）%、（2.07±0.05）%、（5.15±0.12）%和（1.92±0.08）%，其中D90的防治效果最好，防效為54.70%；ITS分子鑒定D90為果生刺盤孢菌Colletotrichum fructicola。接種D90后，玄參CAT酶活性得到顯著提升，在接種第4、6天，PH＋D90處理組CAT酶活性顯著高于葉斑病模型組，同時，D90顯著提升玄參超氧陰離子自由基、木質(zhì)素含量水平積累，但降低了玄參SA、NO的含量。結(jié)論 內(nèi)生真菌D90能有效防治玄參葉斑病，該作用可能與誘導玄參CAT酶活性提升、活性氧的迸發(fā)及木質(zhì)素含量積累有關(guān)。

Objective To screen candidate endophytic fungi for the biocontrol of Scrophularia ningpoensis leaf spot disease and reveal their mechanism. Methods Based on the endophytic fungal strains isolated from S. ningpoensis, the antagonistic strains, were screened by plate confrontation trial with Phoma herbarum (PH) while using Trichoderma harzianum (TH) as an indicator. Control effect of endophytic fungi on the leaf spot of S. ningpoensis was investigated by in vivo leaf inoculation test, and the physiological indexes including plant protective enzyme activity, reactive oxygen species (ROS) level and salicylic acid (SA) content were determined. Further, the biocontrol strains were identified by ITS molecular sequence amplification. Results Among the 72 endophytic fungi tested, a total of 28 strains had significant inhibitory effects on PH, while endophytic fungus D90 had the highest inhibitory rate 0.833% ±0.030%. The results of in vivo inoculation of leaves showed that a total of four endophytic fungi had significant control effects on the leaf spot disease of S. ningpoensis, including D1, D3, D18 and D90, with the proportion of lesion area was (20.53 ±0.32)%, (2.07 ±0.05)%, (5.15 ±0.12)% and (1.92 ±0.08)%, respectively. D90 had the best control effect, with a control effect of 54.70%. D90 was identified as Colletotrichum fructicola. CAT activity of S. ningpoensis was significantly improved after inoculation of D90; On the 4^th and 6^th day of inoculation, compared with the leaf spot model group, D90 significantly increased the superoxide anion radical and lignin content of S. ningpoensis, but decreased the content of SA and NO in S. ningpoensis. Conclusion Endophytic fungus D90 has good biocontrol potential for S. ningpoensis leaf spot disease, this may be attributed to the improvement of CAT activity, ROS burst, and lignin content accumulation.

R286.2

浙江中醫(yī)藥大學松陽研究院科技攻關(guān)專項（SY-Z-2024501）；浙江省重點研發(fā)計劃項目（2021C04029）